Voltage regulating means for rectifiers



Feb. 13, 1940. H. wlNoGRAD 2,189,328

VOLTAGE REGULATING MEANS FOR RECTIFIERS Filed Nov. 23, 1929 5 Sheets-Sheet l 5 Sheets-Sheet 2 Fig. 70.

Attorney ograd -m VW Inventor Harold Win By l H. WINOGRAD VOLTAGE REGULATING MEANS FOR RECTIFIERS Filed NOV. 23, 1929 Fig. 7.

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H. WINOGRAD VOLTAGE REGULATING MEANS FOR RECTIFIERS Filed Nov. 23, 1929 5 Sheets-Sheet 3 Fig. 14.

Inventor Harold Winograd www@ Attorney Feb. 13, 1940.

H. WINOGRAD VOLTAGE REGULATING MEANS FOR RECTIFIERS 5 Sheets-Sheet 4 Filed Nov. 23, 1929 Feb. 13, 1940. H. wxNoc-:RAD

VOLTAGE REGULATING MEANS FOR RECTIFIERS Fiied Nov. 2:5, 1929 5 Sheets-Sheet 5 Fig. 23.

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Harold Wina By w I grad AAAAA VVVVV Patented Feb. 13, 1940 PATENT GFFICE VOLTAGE REGULATING lWEANS FOR REC'EIFIERS Harold Winograd, Collingswood, N. J., assigner,

by mesne assignments, to Allis-Chalmers Manufacturing Company, poration of Delaware Milwaukee, Wis., a cor- Application November 23, 1929, Serial No. 409,298

27 Claims.

. My invention relates to mercury arc rectifier systems and particularly to D.C. voltage regulation in such systems.

The control of D.C. voltage in the mercury fr arc rectifier has commonly been accomplished heretofore by regulation of the rectiiier A.-C. supply, either-by step-by-step regulation of the A.-C. voltage applied to the rectiiier transformer or by phase regulation. These methods are open Ul to the objection that the resulting control of the D.C. voltage is not of suiliciently fine degree or that the regulating means do not follow with sufficient closeness the changes in the D.C. load current. Other methods, also operating by reguf lation of the A.-C. voltage and having for their object a nner degree of D.-C. voltage control, are open to the objection that they involve the use of expensive and complicated control devices.

It is the object of my invention, therefore, to provide improved means for regulating the voltage of the mercury arc rectiiier. A particular object of the invention is to provide means for regulation of the rectifier D.C. voltage by conx trol of the electric eld between the cathode and anodes.

In carrying my invention into effect, regulation of the D.C. rectiier voltage is accomplished by impressing potentials upon control grids placed m between the rectier cathode and anodes.

` Further objects and advantages of the invention will be apparent and a clearer understanding thereof will be obtained from the following description taken with the accompanying drawings 25 in which Figure l is a diagrammatic View of rectiiier apparatus including a D.C. voltage control circuit and illustrating an embodiment of the invention;

2 and 3 are detail views o grid connec- ,m tions in the rectier apparatus shown in Fig. l;

4 and 5 are voltage diagrams illustrating the operation or the system shown in Fig. l;

G and 7 illustrate modications of the D.C. voltage control circuit shown in Fig. l;

Figs. 8, 9 and 10 are diagrammatic views of rautomatic D.C. voltage regulation means for the system shown in Fig. l;

Figs. 1l and 13 are voltage diagrams illustrating the effect on D.C. regulation of a grid voltage ,qu wave having a steep wave front, and Fig. l2 is a diagranxmatic View oi a rectifier apparatus operating in accordance with diagrams il and i3;

Fig. 'l5 is a voltage diagram illustrating the effeet on D. C. regulation of harmonic grid volt- ;,5 ages, and Fie'. 14 is a diagrammatic View of recfill tifier apparatus operating in accordance with diagram l;

Fig. 17 is a voltage diagram illustrating D.C. .regulation by variation of the A.-C. grid potential, and Figs. 16 and 18 are diagrammatic views of rectifierl apparatus operating in accordance with diagram l1;

Fig. is a voltage diagram illustrating D.C. voltage regulation by phase shifting of A.-C. grid voltages and Fig. 19 illustrates rectifier apparatus operating in accordance with Fig. 20; I

Fig. 2l is a diagrammatic View illustrating a modication of the invention in which the D.-C. voltage control circuit is connected to the rectieltransformer neutral, and Fig. 22 is a voltage diagram illustrating the operation of the system shown in Fig` 2l;

Figs. 23 and 24 are diagrammatic views illustrating respectively D.C. voltage control circuits for maintaining a constant current in the load circuit of a rectifier and for limiting the load current.

Fig. 25 is a voltage diagram illustrating a modification of the systems shown in Figs. 4. and 5.

Figure l shows a rectier I comprising anodes 2 to l, control electrodes, as grids 8 to I3, associated with anodes 2 to l respectively, and cathode llt. The anodes are supplied with current from transformer l5 having a primary i6 and secondary il with neutral point I8. The control electrodes 8 to I3 are connected to a polyphase A.-C. supply. In the present embodiment of the invention, the supply for the control electrodes comprises auxiliary windings I9 of rectifier transformer $5, but the said supply may also be obtained from a separate transformer. Current limiting means, as resistances 20, may be inserted in the control electrode leads. The neutral point 2l oi the auxiliary windings is connected to the negative pole of battery 22, the positive pole of which is connected to the cathode I4. The potential of the battery may be varied as by changing the position of connection 23.

shows in detail one of the anodes, as 2, connectedto anode plate 24. A sleeve 25 surrounds anode 2 and its corresponding control electrode, as grid 8, the latter being supported on the sleeve by insulators 2S. A grid terminal 21 is connected to grid 8 through conductor 28 and conductor 29. Terminal 21 is fastened to the conductor as by screw 3l). Conductor 2liv passes through bushing 3l located in the anode plate and is prevented from turning in the bushing by locking plate 32, which is in fixed relation with the conductor and is held in a slot 33 formed in the respectively.

bushing. The Washer 34 is placed between plate and the lower end of the bushing. Conductor 2S is locked to the bushing by nut 35 which projects downwardly Within a recess 35i of the bushing and. hears against Washer 3l. The joint oetween conductor 23 and bushing 3i is sealed by mercury placed between nut 35 and the walls of the recess 36. The portion of conductor 28 which projects below the bushing is lsurrounded by a sleeve 33 supported on insulating bushing 3|. The conduct r 2E joining grid 8 and conductor 28 is enclosed in a sleeve 39, of glass or other suitable insulating and', heat-resisting material, which is located at its ends in sleeves Z5 and 38.

Figure 3 shows a control electrode terminal structure similar in all respects to that shown in 2 except that two sets of terminals 2l, conductors conductors E19 and insulating sleeves 529 are located in a single insulating bushing l0 surrounded hy a single sleeve di'.

In operation of the system shown in Fig. 1, the anodes Il to 'i are supplied from the `secondary -dings il of transformer i5. The anodes will successively assume a maximum positive potential and will, therefore, carry current in secuence. As indicated in Fig. 4, in which Ez Es E4 :represent the Voltage waves of anodes with respect to the rectifier transformer neutral it, the are is transferred from anode to anode at the points of -intersection X. "he DfC, voltage is equal at any instant to the Voltage of the anode carrying current (minus the Volt e drop in. the arc) and has the Value represented hy the succession of Waves E2, E3, E4 intersecting at points X and the resultant average D.C. Voltage is as shown by the dotted line V.

Zi, however, the electric iield between cathode and a given anode is modied hy maintaining the poteifitial between.` the cathode said anode'for example, anode il, lower 'than potential between 'the cathode and the preceding anode, until sonic point, ash, beyond the ini'. rsection ii ci the Waves Egli. is reached.. the current flow y'ill transferred from anode S to anode il only after said. intersection point is reach-ed. As result, tries-hace ci the D.-C. Voltage Wave will he altered, th eoy altering the magnitude of the Dwi?. voltage.

f ssunring that anode 3, corresponding to wave E13 o Fig. e is carrying current: ii afpotential is applied to grid Hl of succeeding anode fl, of such value as to reverse or neutralize the electric held between the cathode and said anode il, until any desired point on the wave Ell, for example, point o, is reached, the arc Will not he transferred from anode Si to anode l until said point b on Wave E4. is reached. Theshape ci the succession of Voltage waves will, therefore, he altered, shown hy the heavy line in Fig. il. and the average D.C. Voltage will have a value shown by line B. maintained until other points on Wave E4, c or c, are reached, the shape of the voltage Wave is altered accordingly and the average Voltage ass-urnes the Values shown by-A and C,

grid. i of anode 5, with respect to cathode ill, at any instant, is equal to the potential at that instant oi that phase of the auxiliary A.-C. sun ply to which said grid is connected, minus the potential of battery 22. At the instant when the grid has a positive mC. potential equal to the cattery potential, the grids potential to the cathode is zero.v In Fig. 5 the sine waves If the potential on grid it of anode is y The potential ci a given grid, as

E3E4 represent the potential of the corra spending anodes 3, 4 to the neutral 9B oi the rectifier supply transformer l5. The sine Wave represents the Efe-C. potential of a grid, as grid ill, to the neutral 2i ci the auxiliary windings iS. Ii the potential of battery 224 the value B2, the potential of grid iii with re'- spect to the cathode ifi is equal to Zero at point b2 corresponding to point in of anode yoltage Wave E4. Before the point b2 is reached, grid it has a negative potential with respect to the cathode, and the transfer of the arc from anode 3 to anode t is, therefore, nre-Vented, When point bz is passed, the potential oi rid i@ to the cathode is positive and the are therefore, trans ferred from anode 3 to anode f1. When the hattery potential has the Value B1, the grid poten tial to the cathode is equal to Zero at the point a2, and the arc will be transferred to anode /2 at a1 of Wave El. When the battery potential has the value B3, the grid potential to the cathode is Zero at point c2, and thearc is transferrea to anode 4 at c1 of wave E4.

It is evident, therefore, that the transfer of the arc from anode to anode may he controlled by varying a D.-C. Voltage, as that of battery which is in series with the Arif). voltage' im# pressed on the grids and that the rectifier D.C. volt g thV 'ehy be controlled.

vInstead of Varying the Df-C. voltage in series with the grids by taps on the battery 22, shown in l, a potentiometer l2 connected across the battery may be employed, as shown in Fig. S. Further, instead of employing a separate source of D.C. potential. a battery 32, for the puroose set forth in connection. with l, the lil-C', output voltage of the rectiier may be utilized by employing a potentiometer 43 connected across the rectifier .ll-C. conductors, shown in Fig?. The neutral. point 2l of the auxiliary windings iii is, in this latter embodiment, connected to the potentiometer and the rectier D.-C. voltage thereby controlled by varying the position of connection 23. A, reactor M may he connected in series with the potentiometer to smooth out the current flow therein and thus prevent the ripple of the rectifier out put ll-C. voltage from coing impressed on 4the control grids.

It is .frequently desirable that the regulation l `matically controlled. in function of the load.

Figure 9 shows another eiuhodiinent of the invention for automatically controlling the rectifier D.-C. output Voltage, which is similar to ythat,

shown in Fig. 8, but diers therefrom in that a Voltage coil 4l, connected across the 1 tiiier D.-C. output voltage conductors, the

regulator i5 to maintain automatically constant the rectifier D.C. output voltage under all load conditions.

Figure l0 shows another embodiment of the invention for automatically controlling the rectiaddition of automatic control means comer D.C. output voltage. In this embodiment, the regulator 45 is provided with two coils, one of which, 41, is actuated as in Fig. 9, in accord ance with the rectifier D.C. output voltage. The other, 48', is connected in one of the rectier D.C. output line conductors in parallel udth a shunt 49 and actuated in accordance with the rectifier output load current.

In order to obtain a closer and more stable regulation of the rectiiier D.C. output voltage, I have found it to be desirable that the A.C. potential impressed on the grids have a steep Wave front within the regulating range. By regulating range is meant the range through which the A.C. potential impressed on a grid intersects the D.C. potential impressed thereon, as shown, for example, by points c2 b2 c2 on the grid potenn tial Wave G4 of Fig. 5. Undesirable variations in the D.C. potential impressed on the grids, which tend to produce instability in the rectier D.C. output voltage control, may be produced either by variation in the voltage of the D.C. source employed for impressing potentials on the grids, or by inaccuracies of the regulator employed for controlling said D.C. voltage. Instability may also result from variations in the electric iields in the rectifier or from changing pressure and temperature conditions in the rectier. The effect of the grid A.C. potential wave shape on the stability of the rectifier D.C. output voltage regulation is shown in Fig. 1l. In this )figure E4 represents the voltage wave of an anode, as anode 4, and G5 Gc represent differently shaped grid voltage waves of the corresponding grid l0. The wave fronts of waves G5 and Ge are, respectively, relatively flat and relatively steep. If the grid operates with the wave G5 having a ilat wave front, any accidental variation of the normal D.-C. grid potential d, as between the values d1 d2, will cause a comparatively large variation v1 of the time of transfer of the arc from anode to anode. If, however, the grid operates with the wave Gs having the steeper wave front, the varying of the grid potential between the limits d1 d2 will cause only a small variation v2 in the time of transfer of the arc from anode to anode. Therefore, by using a steep A.C. voltage Wave on the grid, undesirable variations of the grid D.C. voltage will have a negligible effect on the value of the rectifier D.C. output voltage.

An A.C. potential having a steep wave shape over the regulating range may be obtained by supplying to the grid' an A.C. voltage lagging in phase behind the voltage irnpressed on the anode with which it is associated. One means of obtaining the desired A.C. grid potential is shown in Fig. 1.2 in which the connections from the auxiliary winding I5' to grids 8, 9, lll are displaced relatively to said connections shown in l and as indicated by the heavy line connection between grid 8 and neutral point 2l in Figs. 1 and 12. The connections are so arranged that the A CL voltage applied to a given grid, as grid it, corresponding to anode 4, lags 60 degrees in phase behind the voltage of said anode.

The effect of the change in connections. as shown in Fig. 12, is made clear in Fig. 13 in which E4 represents the voltage wave oi anode t, and

G7 that of the corresponding grid ill. Since grid l voltage wave G7 lags behind anode voltage Wave E4, the zero grid voltage points ci b4 c4 corresponding to the varying D.C. potentials B4 B5 Bs impressed on the grid, will occur on the steep portion of the grid voltage wave. The effect, therefore, on the stability of the rectifier D.C. output voltage regulation will be as hereinbefore explained in connection with Fig. 11.

The phase position of the grid voltages with respect to the anode voltages should be selected to suit the regulating range required, and will 'depend on the number of phases used, the type of transformer connections and other factors. The invention is, therefore, not to be limited to the particular structure described in Fig. 12 but includes all other equivalent arrangements.

An A.C. grid potential having a steep wave iront over the regulating range may further be obtained by impressing on the grids a voltage corresponding in frequency to a harmonic of the A.C. voltage impressed on the anodes, for example, a third harmonic. A grid voltage comprising the harmonic together with the fundamental may be produced by oversaturating the grid auxiliary transformer such as shown in Fig. 12. A harmonic grid voltage without the fundamental may be produced as shown in Fig. 14. In the latter figure the auxiliary transformer is oversaturated and the primary 5l connected in Y with insulated neutral and the secondaries 52 in open delta. 'I'he voltages of the fundamental frequency are, therefore, canceled out, leaving only the harmonic voltages.

The operation of the system shown in Fig. 14 may be better understood by reference to Fig. 15. By employing a third harmonic A.C. voltage on the grids in Fig. 1.4, the voltages of gri-ds 8, Il! and i2, corresponding to the anodes t, 4 and 6 will be of one phase, while the voltages of grids 9, Il and i3, corresponding to anodes 3, 5 and 1, will be of another phase displaced degrees from the phase of grids 8, l0 and l2. The gri-d voltage waves are of steep wave front, for example, Gs, corresponding to anode voltage wave E4. The zero points as be and ce are located on the steep front of wave G8, said points correspending to the varying D.C. potentials Bv Bs B9 impressed on the grids. The resulting effect on the stability of the rectifier D.C. output voltage regulation is as hereinbefore explained in connection with Figs. 11 and 13.

In the systems shown in Figs. 12 and 14, the potentiometer connection across battery 22 may be used, as shown'in 6, or the battery may be dispensed with by employing the potentiometer connection across the rectier D.C. line, as shown in Fig. '7. means shown in Figs. 12 and 14, the rectifier D.C. output voltage may be automatiocally controlled. for example, by the regulating means shown in Figs. 8, 9 and 10.

In the foregoing, the regulating of the rectifier D.C. output voltage is accomplished by impressing on the grids D.C. potentials in series with A.C. potentials and varying the magnitude of the D. C. potential. Instead of varying the potential impressed on the grids, the same result may be obtained by varying the magnitude of the A.C. potential impressed thereon, eithercurrent passing through the exciting winding 55 Further, in the regulating saturate-s the core of the auxiliary .transformer which introduces a harmonic component, for exnk ample, the third harmonic in the voltage wave of secondary 5d. The magnitude of the hai`- monic voltage is a functionk oi the load current. At small loads the harmonic voltage small, and at greater loads it is increased in magnitude.

Fig. 18 shows a regulating means similar tol that of Fig. 16, the D.C. voltage in'ipres'sed on the grids again being constant While the A.C. potential impressed thereon is varied by ineens of the exciting winding 55 `which saturates the core of the auxiliary transformer 155i and produces rthereby a harmonic voltage in the secondary winding of the auxiliary transformer 59. In the regulating means of Fig. 18, however, the transformer is of the form shown in Fig. 11i. The voltages of the fundamental frequency are, therefore, canceled out in the system of Fig. 18, leaving only the harmonic voltages to be irnpressed on the grids.

Referring to Fig. 17 in connection with Fig. 18, the waves G9 represent different values of a harmonic grid voltage wave in the system of Fig, 18, and E4 the corresponding anode voltage wave. With a constant D.C. voltage B10 impressed on the grid, then for varying values of A.C. grid voltage, the corresponding nero grid voltage points are a1 in c1 and the corresponding arc transfer points are da be ca. Since, therefore, the position of the arc transfer point varies with the load current, the rectifier ,D.C. output voltage is varied therewith, as explained in connection wthFig. 1. As a further refinement, non-inductive resistances or reactance coils, as 5t, may be inserted in series with the primary windings to reduce the exciting voltages of transformer 53. f

It will be noted that in the rectifier D.-C. output voltage regulating means, shown in Figs. 16 and 18, it is possible to compensate for the drop in the D.C. output voltage of the rectifier, and thereby to secure either a relatively constant voltage characteristic over the working range or a voltage characteristic rising at increasing loads, that is, an over-compounded characteristic.

In the regulating means shown in Figs. 16 and 18, the regulation of the rectifier D.C. voltage output is secured automatically. The regulation may be accomplished by othermeans, operated manually ii preferred, to vary the A.C.

potential impressed on the grids, while main-` taining constant the D.-C. potentials impressed thereon. For example, the A.C. potential impressed on the grids may be varied by taps 5l' on the primary 5I of transformer 5S, as shown in Fig.v 18. Further, instead of using a separate source of D.-C. grid voltage, as battery 22, either as shown in Figs. 16 and 1S or with the potentiometer across the battery, as shown in Fig. 6, the battery or other separate D.-C. voltage source may be dispensed with, and the D.C. output voltage of the rectifier utilized by means of the potentiometer across the rectifier line, as shown 111 Fig. 7.

In the rectier D.C. output voltage regulating ymeans hereinbeore described, the regulation is accomplished by varying the magnitudes of either the D.-C. or the A.-C. potentials impressed on the grids. The rectifier D.C. output voltage may, however, be controlled without change in the magnitude of either the D.C. or the .lL-C. grid voltages by shifting the phase position of the AWC. voltage impressed on the grids. Fig. 19 shows regulating means in which the potentials impressed on the grids, both the D.C., as battery 22 or other source of yD.-C. potentials, and the 1 -C. potentials, as from windings I9, are constant, and the rectifier D.C. output Volte age control obtained by means of a phase shifter 5B which may be interposed between primary IG of the auxiliary transformer and secondary windings I9.

The operation of the rectifier D.C. output voltage regulating means shown in Fig. 19 will be clear by reference to Fig. 25J in which E4 represents the voltage wave of a given anode and in which G G11 G12 represent the different phase positions of the corresponding constant grid volt-V age wave. With a constant D.C. grid potential B11, and a constant 1 -C. grid potential, the zero point of grid potential is shifted with the phase shift of the A.C. grid potential wave. For A.C. voltage wave positions G10 G11 G12, the zero points are am, D111, e111, respectively, corresponding to the arc transfer points a9 b9 cg of anode voltage wave E1. Since, therefore, the position of the arc transfer point varies with the phase position of the A.C. grid potential wave, the rectifier D.C.vvolt is regulated accordingly.

In the structures hereinbefore described, embodying means for rectifier D.C. output voltage regulation, the control circuit containing the sources of A.C. and D.C. potentials impressed on the grids is shown connected to the cathode. Regulation oi the rectier D.C. output voltage may also be effected by connecting the grid poe tential control circuit, not to the cathode, but to the rectifier transformer neutral point. Fig. 21 shows means for the regulation of the rectiiier D.C. output voltage in which the grid potential control circuit, comprising a D.C. voltage source, as battery 22., and an A.C. voltage source, as auxiliary windings 2l of rectifier transformer l5, is connected to the neutral point I8 of the rectifier transformer secondary I'l.

The operation of the system shown in Fig. 21 will be understood by reference to Fig. 22. In the latter ligure, voltage waves E3' and E4 represent the potential of ancdes 3 and 4 with respect to the neutral. Assuming that the D.C. potential impressed on the grids has a value B12 with respect to the neutral, the voltage wave of grid IG, corresponding to anode 4, will then be G13. When anode 3, the anode next preceding anode t, is operating, the cathode potential is substantially equal to the potential of said anode 3, minus the voltage drop in the arc. The cathode potential is indicated in Fig. 22 by the curve M below voltage wave E3. It

will be seen that the voltage curve G13 of grid y l intersects the cathode potential curve M at point m1. This is equivalent to saying that at point m1, the potential of grid i0 is equal to the cathode potential. Before point m1 is reached, the potential of grid i0 is less than that of the cathode, that is, the grid potential up to the point m1, is negative with respect to the cathode and does not become zero with respect thereto until point m1 is reached, Since the arc cannot be transferred to anode 1, the next anode following anode 3, as long as its grid i is negative with respect to the cathode, the are is transferred to said anode i only when Zero point mi is reached.

Assuming the grid D.-C. potential to be changed to sorne other value, as M13, with respect to the neutral, the voltage wave of grid l@ will then be G11. The point of intersection thereof with cathode curve M will be m2, at which point the arc will be transferred to anode li. The time of transfer of the arc from anode to anode, and the rectier D.C. output voltage varying in accordance therewith, may, therefore, be controlled by varying the D.C. potential impressed on the grids.

Figure 23 shows means for maintaining a constant current in a rectifier load circuit by the regulation of the rectifier D.C. output voltage through the varying of potentials impressed on the rectiiier grids. The neutral point 2| of the windings i9, which impress A.-C. potentials on the rectifier grids, is connected to a rheostat 59 across the rectifier D.C. output circuit. The rheostat is operated by a motor 60 controlled by a current relay 6I. The relay is connected to a shunt 62 in the rectifier D.C. output circuit. So long as the current in the rectifier D.C. output circuit remains within predetermined limits, the relay remains in the neutral position. If the current is too 10W, contact 63 of the relay is closed and the motor is operated to move the rhcostat arm in clockwise direction, reducing the D.C. potential impressed on the grids in series with the A.C; potential from winding i9, thereby raising the rectifier D.C. output voltage until the load current is restored to a value within the predetermined limits when contact 63 is again opened. If the load current is too high, Contact 64 is closed causing the rheostat arm to move in counterclockwise direction, thereby reducing the rectifier D.C. voltage until the load current is again restored to a value within the predetermined limits.

Fig. 2li shows means for limiting a rectifier load by the regulation of the rectifier D.C. outut voltage through the varying of potentials impressed on the rectier grids. In this embodiment, tlie potentiometer 43 is connected across the rectifier D.C. output circuit, as in Fig. 7. Two load-limiting steps are shown in Fig. 24, as controlled by current relays 65 and 66 connected to shunt Si in the rectiiier D.C. output circuit. When the load current exceeds a predetermined value, the relay E closes its contact, short-circuiting part of the resistance in potentiometer 43, thereby raising the potential of connection point 23 with respect to the cathode. The transfer of the arc from one anode to another is, therefore, retarded and the rectifier D.C. output voltage is reduced. If the current rises still higher after relay 65 has operated, relay 66 then operates short-circuiting more of the resistance and thereby further reduces the rectifier D.C. output voltage.

Numerous modifications are possible in the means operating by control or the rectifier D.C. output voltage for maintaining constant current in the rectifier load circuit, as shown in Fig. 23, and for limiting the rectier load, as shown in Fig. 24, and any of the means hereinbefore described for rectifier D.C. output voltage regulation may be employed.

In the hereinbefore described rectiiier D.C. output voltage regulating means, the electric iield between cathode and anodes is modiiied and the regulation thereby obtained by impressing on the rectifier grids potentials of such magnitude and so phased with respect to the anode Waves as to prevent transfer of the arc to successive anodes until the intersection point of the anode Waves is passed. The electric field between cathode and anodes may, however, be modified and the desired rectifier D.C. output voltage regulation obtained by impressing on the grids potentials .of such magnitude and so phased that the arc is, transferred to successive anodes before the intersection point of the anode waves is reached. The latter method of control will be clear by reference to Figs. 25 and 13 in connection with Fig. 1.

In Fig. 25, E2 E3 E4 represent, respectively, the voltage Wages on anodes 2, 3, 4 Assuming anode 3, corresponding to voltage wave E3, is in operation, then, if the electric field between the cathode and anode 3 is modied by impressing potentiais on the corresponding grid so that the potential between the cathode and said anode reduced below the potential between the cathode and succeeding anode 4 at a point b, before .intersection point X is reached, the arc will be transferred to t at said point b. rl`he rectifier D.C. output voltage wave will have the `iape shown in the heavy line in Fig. 25 and the rectifier D.C. output voltage will have the average value oi line B. If potentials impressed on grid i) are varied so that the points at which the arc is transferred to anode d are a or c, the rectifier D.C. output voltage wave will llave the values represented by lines A and C, 1respectively. In Fig. i3 is illustrated one means eifecting the result described in connection with Fig. 25. In this embodiment wave G15 represents the potential or the grid corresponding to the anode Whose voltage wave is E5. Grid voltage Wave G15 is shown as leading, for example, by 60 degrees the corresponding anode wave E5. -With different DAS. potentials Bi B6 impressed on the grid, the zero points of grid potential are an bi1 cii. :since the grid voltage leads the corresponding anode voltage, the points at which the arc is transferred occur at diz bis C12 before the intersection X or E5, with the succeeding anode voltage wave, is reached. The rectifier D.C. output voltage therefore, regulated by varying the D.C. potential impressed on tlie grids. Other control means disclosed herein may be used to eiiect the rectifier D.C. output voltage regulation which operates as described in connection with Fig. 25.

Various embodiments of my invention have been described herein for the purpose of illustration. It will be understood, however, that modiiications in the structures disclosed may be made Within the spirit of the invention, and Without departing from the scope thereof as defined in the appended claims.

The invention claimed is:

l. In an electrical system, the combination with an electric current rectifier of the metallic vapor arcing type having an anode, and a control electrode, and means for impressing A.C. potentials on said anode, oi means for impressing on said control electrode voltage waves corresponding in frequency to harmonics of the potentials impressed on said anode, and means for impressing D-C potentials on said control electrode.

2. The combination in a rectifier system comprising an electric current rectifier of the metallic vapor arcing type having an anode, and a control electrode, input and output circuits, and means for impressing A.-C. potentialsy on said anode, of means for impressing on said control electrode voltage Waves corresponding to harmonies of the potentials impressed on said anode, means associated with said output circuit for impressing D.-C. potential on said control electrode, and means responsive to changes in an electrical condition in at least one of said circuits for controlling said voltage waves impressed upon said control electrode.

3. The combination in a rectifier system coniprising an electric current rectifier of the metallic vapor arcing type having an anode, and a control electrode, and means for impressing fn-C. potentials on said anode, of means for impressing D.C. potential on said control electrode, means for imn pressing on said control electrode voltage waves corresponding .in frequency to harmonics of the potentials impressed on said anode, and means in operative relation with the means for impressing the voltage waves on said control electrode for controlling said voltage Waves.

4. In combination with a rectifier system comprising an electric current rectifier of the metallic vapor arcing type having an anode, and a control electrode, an output circuit, and means for impressing A.C. potentials on said anode, ci means `for impressing D.C. potential on said control electrode, means for impressing on said control electrode voltage waves correspondingin yfrequency to harmonics ofthe potentials impressed on said anode and means responsive to an elecn trical condition in said output circuit and in koperative relation with the means for impressing cathode, means for controlling the voltage in said D.C. circuit comprising means connected with said source of A.C. for impressing a voltage on said control electrode, a resistance connecting said control electrode With said D.C. circuit to impress a direct current voltage on said electrode,

yan oscillating contact for gradually varying the voltage impressed on said control electrode, and a coil moving said contact in response to variations of voltage in said D.C. circuit.

6. In a current rectifying system comprising v an electric current rectier of the metallic vapor arcing type having a casing, an anode, a cathode, and a control electrode, a source `of A.C. connected with and supplying said anode, a circuit connected with and receiving D.C. from said cathode, means for controlling the voltage in said D.C. circuit comprising means connected with said source of A.C. for impressing voltage waves on said control electrode, a resistance connecting said control electrode with said D.C. ircuit to impress a direct current voltage on said electrode, an oscillating contact for gradually varying the voltage impressed on said control electrode, and a plurality of cooperating coils energized from said D.C. circuit for operating said contact, one of said coils being responsive to current and the other of said coils beingv responsive to voltage.

7. In a current rectifying system comprising an electric current rectier of the metallic vapor arcing type having a casing, an anode, a cathode, and acontrol electrode, a source of A.C. connected with and supplying said anode, a circuit connected with and receiving D.C. from said cathode, means for controlling the voltageY in said D.C. circuit comprising means connected with, said source of A.C. for impressing voltage Waves on said control electrode, a resistance connecting said control electrode with said D.C. circuit to impress a direct current voltage on said electrode, an oscillating Contact for gradually varying thev voltage impressed ony said control electrode, and a coil connected with said A.C.

source and responsive to the current therein for operating said contact.

8. In a current rectiiying system comprising an electric current rectifier of the metallic vapor arcing type having a casing, an anode, a cathode,

electrode, an oscillating contact for gradually.

varying the voltage impressed on said control electrode, a motor for operating said contact, and a current relay `connected into said D.C. circuit and controlling said motor in response to the load thereon.

9. In a rectifier system comprising an electric current rectifier of the metallic vapor type having an anode and a control electrode, acircuit for impressing alternating current on said anode, a direct current output circuit, means for con trolling the voltage o said output circuit by varying the shape oi the wave thereof comprising means in operative relation with said alternating current circuit for impressing voltage Waves on said control electrode and for changing the phase thereof with respect to the phase of the potentials impressed on said anode, and means having connections for impressing direct current voltage on said electrode from the said output circuit, the said connections including a reacts-nce coil included therein for reducing in said connections ripple currents received therein fromsaid output circuit.

.10. In a rectifying system comprising an electric current rectifier of the metallic vapor arcing -type having an anode, a cathode, and a control electrode, a source of alternating current connected with .and supplying said anode, an output circuit connected With and receiving direct current from said cathode, means for controlling the voltage of the said output circuit comprising means connected With said source of alternating current for impressing a voltage on said control electrode, a resistance divided into sections connecting said control electrode with said output circuit for impressing direct current voltage from said output circuit on said control electrode, and means for varying said resistance by rendering ineffective sections thereof to thereby vary the magnitude of the said direct current voltage impressed on said control electrode, the last said means comprising a vplurality of relays selectively actuated in dependence upon the magnitude of the current flowing in said output circuit.

il. In combination with a rectifier system. com prising an electric current rectifier of the metallic vapor arcing type hai-ing an anode, a cathode, and a control electrode, a source of alternating current connected with said anode for impressing alternating current potentials thereon, adirect current output circuit connected with' said cathode to oe supplied with direct current from said rectifier', oi means comprising a transformer having a primary winding connected with said source ci alternating current and an open delta connected secondary winding connected with and operative to impress voltage Waves upon said control electrode correspoi'iding in frequency to liarmonies of the potentials impressed on said anode, and means responsiveto current iiow in said outlil i) put circuit and in operative relation With said means for impressing voltage Waves on the said control electrode for controlling said voltage waves.

12. In combination Witn a rectifier system coinprising an electric current rectifier of the metallic vapor arcing type having an anode, a cathode, and a control electrode, a source of alternating current connected with said anode to supply alternating currenf*u to said rectier to be converted into direct current, and an output circuit connected with said rectiiier to be supplied with direct current therefrom, of means comprising a transformer having a primary Winding connected with said source of alternating current and an open delta connected secondary Winding con-- nected with said control electrode to impress` thereon voltage waves corresponding in frequency to harmonics of the voltages of the said source of current connected with said anode, means responsive to ow of current in the said output circuit and in operative relation with said transformer for controlling said voltage Waves on said control electrode, and a source of direct current connected with said output circuit and said delta connected Winding for impressing direct current voltage on said control electrode.

13. In combination with an electric current rectiier of the vapor arcing type having an anode and a control electrode, a source of A.C. connected With and supplying said anode, and a circuit connected With and receiving D.C.l from said rectier, of means for controlling the voltage of said circuit comp-rising means Aconnected with said source oi ,A.C. for impressing voltage Waves on said control electrode, a voltage divider connected across said circuit, and means connecting said voltage divider with said electrode whereby DfC. voltage is impressed cn said electrode from said circuit.

14. In combination with an electric current rectifier of the vapor arcing type having an anode, and a control electrode, a source of A.C. connected with and supplying said anode, and a circuit connected with and receiving D.C. from said rectiiier, `oi ymeans for controlling the voltage of said circuit comprising means connected with. said source of rL-C. for impressing voltu age Waves on said control electrode, a voltage divider including a reactance connected across said circuit, and means connecting said voltage divider with said electrode whereby D,-C. voltage is impressed on said electrode from said circuit and ripple current received therefrom is suppressed.

15. In combination with an electric current rectier of the vapor arcing type having an anode, and a control electrode, asource of A.C. connected with and supplying said anode, and a circuit connected with and receiving D.C. from said rectifier of means for controlling the voltage of said circuit comprising means connected with said source of A.C. for impressing voltage waves on said electrode, a voltage divider including an inductance connected across said circuit, and means connecting said'voltage divider with said electrode whereby D.C. voltage is impressed on said electrode from said circuit and voltage ripples of said voltage is suppressed.

16. In combination with an electric current rectifier ci? the vaporarcing type having an anode, and a control electrode, a source of A.-C. connected with and supplying said anode, and a circuit connected with and receiving D.C. from said rectier, of means for controlling the voltage of said circuit comprising means connected with said source of A.-C, for impressing voltage waves on said control electrode, a voltage divider connected across said circuit, means connecting said voltage divider with said electrode Whereby D.C. voltage is impressed on said electrode from said circuit, and means for varying the connection of the last said means with said voltage divider to thereby gradually vary the magnitude of said D.C. voltage impressed on said electrode.

17, In combination with an electric current rectifier of the vapor arcing type having an anode,

a control electrode, a source of A.C. connected with said anode and supplying said rectigder, and a circuit connected with and receiving D.C. from said rectiner, of means for controlling the voltage of said circuit comprising means connected With said source ci A.C. for impressing voltage Waves on said control electrode, a voltage divider connected across said circuit, means connecting said voltage divider with said electrode whereby D.-C. voltage is impressed on said electrode from said circuit, means for varying the connection of the last said means 'with .said voltage divider to thereby gradually vary magnitude of said D.-C. voltage impressed on sai-d electrode, and means operable responsive to and in dependence upon changes in conditions of said circuit for actuating the said means for varying the said connection of the said voltagedivider with the said electrode. i8. In combination with electric current rectiler oi the vapor arcing type having an anode, and a control electrode, input and output circuits, and means impressing A.C. potentials on said anode, of means for impressing on said control yelectrode voltage Waves having Wave fronts steeper the corresponding portions of sinusoidal voltage waves of the same amplitude as said voltage waves and of the same frequency as said A.C. potentials, and means for impressing D.C. potentials on said electrode.

19. In an electric translating circuit, a source oi alternating potential, an electric valve provided with an anode, a cathode, and a control grid, a saturable transformer for energizing said grid from said source, and means for controlling the saturation of said transformer for controlling the conductivity of said valve.

20. The method of controlling the conductivity of a grid controlled electric valve excited from a saturable transformer connected to a source of alternating potential which comprises varying the saturation of said transformer to vary the point in the cycle of alternating potential at which said valve is rendered conductive,

21. In a regulating system, an electric circuit, an electric valve provided with an anode, a cathode and a control electrode for controlling an electrical condition of said circuit, a source of alternating potential connected to energize the anode oi said valve, means for impressing on said control electrode an alternating potential of substantially constant value and xed phase relation With respect to said anode potential, and means for superimposing a unidirectional potential varying in accordance With the electrical condition to be regulated on the alternating potential of said control electrode in a manner to vary the conductivity vof said valve in proportion to the deviation from a predetermined value of the electrical condition to be regulated.

22. In an electric current converting system, the combination with an alternating current circuit, a direct current circuit, and means comprising an electric valve having an anode and a cathode constituting spaced electrodes for the flow of current therebetween, of means for controlling said ow of current comprising an element of said valve other than said electrodes, means for impressing on said element a voltage comprising an alternating component correspending in frequency to a harmonic of the Voltage frequency of said alternating current circuit and a unidirectional component, and means for varying the magnitude ci said unidirectional component.

23. ln an electric current converting system, the combination with an electric current supply circuit, an electric current work` circuit, and means comprising an electric valve having an anode and a cathode interconnecting said circuits and constituting spaced electrodes for the flow of current therebetween, of means for controlling said flow of current comprising an element oi said valve other than said electro-des, means for impressing a unidirectional voltage component on said element, means comprising a saturable transiormer for impressing an alternating Voltage component on said element, and means :for varying the said alternating Voltage component comprising means for varying the saturation of said transformer. y 24. In an electric current converting system, the combination with an alternating current circuit, a direct current circuit, and means cornvprising an electric valve having an anode and a cathode interconnecting said circuits and constituting spaced electrodes for the flow of currentl therebetween, oi means for controlling said fiow of current comprising an element oi said valve other than said electrodes, means for impressing on said element alternating voltage components having wave fronts steeper than the corresponding portions of sinusoidal waves of the same amplitude as said voltage Waves and of the same freduency as the voltage waves of said alternating current circuit, means for impressing a unidirectional voltage component on said element, and means for varying the said alternating voltage component.

25. In an electric current converting system, the combination with an alternating current circuit, a direct current circuit, and means comprising an electric valve having an anode and a cathode interconnecting said circuits and constituting spaced electrodes ici' the flow or current therebetween, of means or controlling saidow of current comprising an element of said valve other than said electrodes, means i'or impressing on said element alternating 'voltage components having wave fronts steeper than the corresponding portions of sinus idal waves of the same amplitude as said voltage waves and of the same frequency as the voltage Waves of said alternating current circuit, for impressing a unidirectional voltage component on said element, and ineans operable dependence upon variations in the magnit de oi said current flowing in said direct current circuit for varying the said alternating voltage component.

26. In an electric current converting system, the combination with an electric current supply circuit, an electric current Work circuit, and means comprising an electric-valve having an anode and. a cathode interconnecting said circuits and constituting spaced electrodes for the flow of current therebetween, oi meansfor controlling said flow oit current comprising an element of said valve other than said electrodes, a control circuit for said element comprising a source of negative. bias potential and a saturable transformer, a source of control potential for energizing said transformer, and means comprising an element of said transformer operable in dependence upon variations in sid iow ol current through said valve to control the saturation of said transform tc thereby modify the eiect of said control circuit.

27. In 'an electric current converting system,

the voltage oi said. alternating current circuit for determining the moments oi nitiation'oi the periods of said iiow of current between said anode and cathode.

HAROLDY WINOGRAD. 

